Semiconductor device package with improved cooling

ABSTRACT

A chip scale package has a semiconductor MOSFET die which has a top electrode surface covered with a layer of a photosensitive liquid epoxy which is photolithographically patterned to expose portions of the electrode surface and to act as a passivation layer and as a solder mask. A solderable contact layer is then formed over the passivation layer. The individual die are mounted drain side down in a metal clip or can with the drain electrode disposed coplanar with a flange extending from the can bottom. The metal clip or drain clip has a plurality, a parallel spaced fins extending from its outwardly facing surface.

RELATED APPLICATION

This application claims the benefit and priority of U.S. ProvisionalApplication No. 60/328,362 filed Oct. 10, 2001 entitled SEMICONDUCTORDEVICE PACKAGE WITH IMPROVED COOLING and which is incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to semiconductor device packages and morespecifically relates to a novel semiconductor device package with afinned heat sink for improved cooling.

BACKGROUND OF THE INVENTION

This invention relates to semiconductor devices and more specificallyrelates to a process for the low cost manufacture of a novelsemiconductor device.

In prior art semiconductor devices, the housing area is frequently alarge multiple of the area of the semiconductor die contained therein.Further, in many known semiconductor device, heat is taken out only fromone side of the die, usually the bottom surface. In addition, theprocess for the manufacturing of prior art semiconductor devices iscostly, specially when single device handling techniques are used.

In the presently known semiconductor die, particularly power MOSgateddie, the top electrode (the source) is generally an aluminum contactcontaining about 1.0% silicon (hereafter an aluminum contact). Thealuminum contact is used because it is well adapted to the wafermanufacturing process. However, it is difficult to form electricalconnections to such aluminum contacts so a wire bond process is usuallyused in which a wire is ultrasonically bonded to the underlying aluminumcontact. These wire-bond connections have a limited area and are thus asource of electrical resistance (R_(DSON)) and of heat generation duringoperation. However, the bottom drain contact of a conventional MOSgateddie is frequently a trimetal which is easily solderable or otherwiseelectrically connectable to a wide area contact surface without wirebonding as shown, for example, in U.S. Pat. No. 5,451,544. Thus, heat isprimarily removed from the silicon die at the back contact surface, eventhough most heat is generated at the junction in the top surface and atthe wire bonds. It would be desirable to remove heat from such a bottomdrain in an improved manner.

It is known that solderable top contacts can be made to the top surfaceof a die, as shown in U.S. Pat. No. 5,047,833. However, the packagesused for such solderable top contact structures have had very large“footprints” in comparison to the die area.

It would be desirable to produce a semiconductor device and a processfor its manufacture which would occupy a smaller area on a circuit andwould exhibit a lower R_(DSON) than the known semiconductor devices.

It would be further desirable to produce such devices in a process whichpermits batch handling with reduced equipment on the production line andlower costs.

Devices are known in which the source side of a MOSgated device wafer iscovered with a passivation layer, preferably a photosensitive liquidepoxy, or a silicon nitride layer, or the like. To form the passivationlayer, the wafer is coated by spinning, screening, or otherwisedepositing the liquid epoxy onto the wafer surface. The material is thendried and the coated wafer is exposed using standard photolithographicand masking techniques to form openings in the passivation layer toproduce a plurality of spaced exposed surface areas of the underlyingsource metal and a similar opening to expose the underlying gateelectrode of each die on the wafer. Thus, the passivation layer acts asa conventional passivation layer, but further acts as a plating resist(if required) and as a solder mask, designating and shaping the solderareas. The openings in the novel passivation layer can be made throughto a conventional underlying solderable top metal such as atitanium/tungsten/nickel/silver metal. Alternatively, if the underlyingmetal is the more conventional aluminum metal the exposed aluminum canbe plated with nickel and gold flash or other series of metals,resulting in a solderable surface, using the passivation as a platingresist. The tops of the plated metal segments are easily solderable, orotherwise contacted with low resistance, as compared to the highresistance connection of the usual wire bond to an aluminum electrode.

The source contact areas may have various geometries and can evenconstitute a single layer area region.

The wafer is then sawn or otherwise singulated into individual die. Theindividual die are then placed source-side down and a U-shaped, anL-shaped or a cup shaped, partially plated drain clip is connected tothe solderable drain side of the die, using a conductive epoxy orsolder, or the like to bond the drain clip to the bottom drain electrodeof the die. The bottoms of the posts of the drain clip may be coplanarwith the source-side surface (that is the tops of the contactprojections) of the die, or the source-side surface may be offsetinwardly with respect to the bottoms of the post to improve reliability.The outer surface of the die is then overmolded in a mold tray. A largenumber of die with such drain clips can be simultaneously molded in themold tray.

The bonding material may be protected with a fillet of passivationmaterial or by overmolding all, or a part of the assembly. The parts canbe made in production by using a lead frame, a continuous strip, or bymolding devices in a single block and singulating devices from thatblock.

After molding, the devices are tested and laser marked and are againsawn into individual devices.

Devices of this kind are shown in a copending application Ser. No.09/819,774, filed Mar. 28, 2001 entitled CHIP SCALE SURFACE MOUNTEDDEVICE AND PROCESS OF MANUFACTURE, the disclosure of which isincorporated herein by reference.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with the invention the bottom of a die, that is, theupward facing drain or other power contact of a semiconductor die, is atleast thermally connected to a conductive heat sink with a finnedstructure. Such a structure is particularly useful in applications whichemploy forced air cooling such as servers, in which the heat sink may beseveral millimeters thick; or in lap top or other applications, in whichthe heat sink may have a thickness of only ½ millimeter. The heat sinkmay be connected to the die as by a conductive solder, or a conductiveadhesive such as a silver filled epoxy. The heat sink itself may be madeof any suitable conductive material such as aluminum or metal-matrixpolymer/epoxy and can be extruded, formed or molded.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a singulated power MOSFET die which can behoused in accordance with the invention.

FIG. 2 is a cross-section of FIG. 1 taken across section line 2—2 inFIG. 1.

FIG. 3 is a top view of the die of FIG. 1 after it has been processed todefine a plurality of separate “solderable” source contact areas and a“solderable” gate area.

FIG. 4 is a cross-section of FIG. 3 taken across section line 4—4 inFIG. 3.

FIG. 5 is a view like that of FIG. 3 of a die with a modified sourcecontact pattern.

FIG. 6 is a view like that of FIGS. 3 and 5 of a still further and largearea “solderable” source contact pattern.

FIG. 7 is a top view of a still further contact topology (with a cornergate).

FIG. 8 is a cross-section of FIG. 7 taken across section lines 8—8 inFIG. 7.

FIG. 9 is a perspective view of a drain clip which can be modified inaccordance with the invention.

FIG. 10 is a top view of the drain clip of FIG. 9, with mold lockopenings formed in the clip.

FIG. 11 is a bottom view of the subassembly of the die of FIGS. 3 and 4and the clip of FIG. 9.

FIG. 12 is a cross-section of FIG. 11 taken across section line 12—12 inFIG. 11.

FIG. 13 shows the subassembly of FIGS. 11 and 12 after overmolding in amolding tray.

FIG. 14 is a cross-section of FIG. 13, taken across section lines 14—14in FIG. 13.

FIG. 15 is a cross-section of FIG. 13 taken across section line 15—15 inFIG. 13.

FIG. 16 is a perspective view of a further embodiment of a drain clipwhich can be modified by the invention.

FIG. 17 is a top view of the clip of FIG. 16.

FIG. 18 is a bottom view of assembly of the clip of FIGS. 16 and 17 witha die of the general kind of that of FIGS. 3 and 4 after overmolding.

FIG. 19 is a cross-section of FIG. 18 taken across section line 19—19 inFIG. 18.

FIG. 20 is a bottom view of a cup shaped drain clip with a die of thetopology of FIGS. 7 and 8.

FIG. 21 is a cross-section of FIG. 20 taken across section lines 21—21in FIG. 20.

FIG. 22 shows a wafer of MOSFET die before singulation.

FIG. 23 shows process steps for the formation and patterning of apassivation layer on the source surface of the wafer of FIG. 22.

FIG. 24 shows the metalizing atop the passivation layer of FIG. 23.

FIG. 25 is an isometric view of the novel drain clip according to theinvention.

FIG. 26 is a top plan view of the clip of FIG. 25.

FIG. 27 is a side plan view of FIG. 26.

FIG. 28 is an exploded perspective view of the modified drain clip ofthe invention as applied to a die and a support board.

FIG. 29 shows the structure of FIG. 25 after assembly.

FIG. 30 is a front plan view of FIG. 29.

FIG. 31 is an enlarged view of a portion of the device shown by FIG. 30.

FIGS. 32a and 32b show side and top views of a clip according to analternative embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention provides a novel package for semiconductor die ofthe kind having power or other electrodes on opposite surfaces of thedie and makes it possible, with low cost manufacturing techniques, tomake both electrodes available for surface mounting on a common supportsurface, for example the metallized pattern on a printed circuit boardwith improved cooling. While the invention is described with referenceto a vertical conduction power MOSFET having the gate and sourceelectrode on one surface and a drain electrode on the opposite surface,the invention is equally applicable to IGBTs, thyristors, diodes and thelike of various topologies.

Thus, as will be seen, a novel die clip surrounds and contacts at leasta portion of the back side electrode (a drain electrode in a MOSFET) andat least one post of the clip extends over an edge of the die andterminates in a plane which is coplanar with, but insulated from thefront surface contacts (gate and source in a MOSFET) and the die clipacts as a good heat sink by virtue. The device may then be overmoldedaround the back and sides of the die and clip to present flat, coplanarsolderable contact surfaces for all die electrodes to a mountingsurface.

All top contact surfaces are formed, using a novel solder mask to formeasily solderable contact surfaces on the die top surface, while the dieare in the wafer stage. Drain clips are then attached to the die afterdie singulation and are overmolded in a batch molding process.

FIG. 1 shows a typical power MOSFET 30 to which the invention can apply.The die 30 may be of the type shown in U.S. Pat. No. 5,795,793 but canbe any kind of die having a junction containing silicon body 31, a topaluminum (that is, aluminum with 1.0% silicon) source electrode 32, analuminum gate electrode 33 and a bottom drain electrode 34 (FIG. 2),which may be a conventional easily solderable trimetal. The top aluminumlayer may be any other suitable metallic material. Connections arenormally made to aluminum electrodes 32 and 33 by wire bonding.

As will be later described, a plurality of easily solderable contactposts 36 are secured to (formed on) the source electrode 32 and acontact post 37 is secured to the gate electrode 33 as shown in FIGS. 3and 4. Contacts 36 and 37 are sub-flush by the thickness of thepassivation in the case of a silver top metal die, and by about one-halfthe passivation thickness in the case of a plated aluminum top metaldie. The flat contact tops are coplanar. Contact to these contactsurfaces is made by a solder paste, which at minimum printable solderthickness is about 4 to 5 times as thick as layer 38, which is thepassivation layer residing on the top surface of the die.

The pattern of contacts 36 can take different forms such as those shownin FIGS. 5, 11 and 18. Further, it is also possible to use a large areasolderable contact such as source contacts 40, for the die of FIG. 6 andFIGS. 7 and 8. A metallizing process for forming contacts 36, 37 and 40shall be later described.

In forming the package with die prepared as shown in FIGS. 3 to 8, aconductive plated (or partly plated) metal clip 45 of FIG. 9 isemployed. Clip 45 may be a copper alloy with at least partially platedsilver surfaces where contact to other surfaces is to be made. As willbe later described, clip 45 is modified with fins for improved cooling.

Clip 45 has a general “U-shape” with shallow posts 46 of a lengthslightly greater than the thickness of die 31 as measured from thesurface 47 to the free surfaces of columns 36, 37, plus the thickness ofan adhesive used to connect the drain to the plated interior surface 47of the flat thin web 48 of the clip. For example, the clip may have atotal thickness along the full length of posts 45 of 0.7 mm and a lengthfrom surface 47 to the free end of posts 46 of about 0.39 mm. Thedistance between the posts 46 depends on the size of the die, and adistance of 5.6 mm has been used for a size 4.6 die of InternationalRectifier Corporation, with a total width of about 1.5 mm for each ofposts 46.

Mold lock openings 48 and 49 may also be formed in the clip 45 as shownin FIG. 10.

The solderable bottom drain electrode 34 of the die 30 is electricallyconnected to and secured to the plated interior of drain clip 45 as by aconductive adhesive 60 as shown in FIGS. 12, 29, 30 and 31. The adhesivecan, for example, be a silver loaded epoxy material which is suitablycured. Gaps 61 and 62 are left between the side edges of die 30 and theopposite sides of posts 46 of clip 45.

In the embodiment shown, the structure is dimensioned so that the freesurfaces of posts 46 (the drain connector) and posts 36 and 37 arecoplanar. In a preferred embodiment, the source electrode of the die maybe offset inwardly in relation to free surfaces of posts 46 in order toimprove the reliability of the device.

Thereafter and as shown in FIGS. 13, 14 and 15, the device of FIGS. 11and 12 is overmolded with mold compound 70 in a mold tray. Mold compound70 lies over the full exposed outer surface of clip 45, except for theouter free surfaces of posts 46. Mold compound fills into the gaps 61and 62 as shown in FIGS. 13 and 15. The device is now ready for surfacemounting to conductive traces on a printed circuit board, which arealigned with contacts 36, 37 and 46.

FIGS. 16 to 19 show a further embodiment of a device which can bemodified by the invention, using a different clip geometry. Thus, theclip 80 of FIGS. 16 and 17 has a web 81 and three segmented projectingposts 82, 83 and 84. A die 30, which has projecting contacts 36 and 37is first adhered, at its drain contact (not shown) to web 81 as shown inFIGS. 18 and 19 so that contacts 36, 37 and the free surfaces of drainclip projections 82, 83 and 84 lie in a common place. The device is thenovermolded with molded compound 70 in a suitable mold tray.

FIGS. 20 and 21 show a still further embodiment of a package that may bemodified according to the present invention in which the die of FIGS. 7and 8 is mounted in a cup-shaped clip 100 which is a silver platedcopper alloy. Clip 100 has an internal area greater in length and widththan the die 30, and, the bottom drain electrode of die 30 is connectedto the interior web surface 101 (FIG. 21) by silver loaded (conductive)epoxy 102, which is cured. Optionally, a ring of low stress highadhesion epoxy 103 may be applied around the die edge, sealing andadding structural strength to the package.

The top surface of solderable contact 40 is coplanar with drain clipprojection surfaces 105. Thus, all of contacts 105, 40 and 27 will alignwith contact traces on a printed circuit board. The drain contacts maytake any suitable form and could comprise a single contact or side, ifdesired.

FIGS. 22 to 24 show a process for forming conductive posts on thealuminum electrodes of a conventional die. Thus, a plurality ofidentical die, each having a gate electrode 37 and separate sourceelectrodes (not numbered) are shown within wafer 110 prior to diesingulation. While still in wafer form, the top surface of the wafer 110is coated with a photoimagable solder mask 111. Mask 111 is aphotosensitive liquid epoxy which will act as a passivation layer, aplating resist (if required) and a solder mask designating and shapingthe solder areas. However, other mask materials, for example, siliconnitride, can be used. Using a conventional reticule, multiple openings111a to 111d are formed through the mask to the underlying source andgate contacts on the die top metal. A laser etch process can also beused to form these openings.

As shown in FIG. 24, a series of metals 112 are then plated stop thesurface of the wafer and the plating adheres to the metal of source 32(and other electrodes) which are exposed through openings 111a to 111d,forming contacts 112a to 112d with the source and a similar contact tothe gate. Metals 112a to 112d can consist of a first layer of nickelwhich makes good contact to the aluminum, followed by a gold flash.Alternatively, the nickel can be followed by layers of copper or tin,and the like, ending with an easily solderable metal top surface such asilver.

The wafer is then sawn to separate the die at lines 112 and 113 forexample, and the die are singulated. The typical die 30 has theappearance shown in FIGS. 3 to 8 and has a plurality of solderablesource contacts and gate contacts which project above insulation surface38.

The singulated die are then placed drain source-side down, intoconductive clips which are plated on their interior with silver or someother conductive coating. The die is bonded to the clip, usingconventional bond material such as a conductive epoxy as previouslydescribed. The clips/cans can be presented in the form of a lead frameand the devices can be later singulated from the lead frame.

According to the present invention, the clip 45 (or 80 or 100) can bemodified to improve the dissipation of heat that is generated by the die30. Referring to FIGS. 25-27, a modified clip 45, for example, wouldinclude a web portion 201 having a free surface from which a pluralityof cooling fins 200 extend away. According to an aspect of the presentinvention, web portion 201 can have an increased thickness for betterheat extraction and spreading. In the embodiment shown by FIGS. 25-27,the clip 45 includes two posts 46 disposed at opposing edges of webportion 201 and extending away from the surface of web portion 201 whichis electrically connected to an electrode of die 30, as will beexplained later. The plurality of cooling fins 200, the two posts 46 andthe web portion 201 are integrally connected to one another and form aunitary body, which may be made of aluminum, a metal matrix polymer,copper, a copper alloy or some other suitable thermally conductivematerial through extrusion, molding or some other suitable method. Ofcourse, it should be recognized that a clip according to the presentinvention is not necessarily limited to the configuration shown by FIGS.25-27 and may, for example, include fewer or more posts disposed atother positions.

Referring now to FIGS. 28-29, the back drain 34 of die 30 isconductively attached to the clip 45 by solder or by a conductive silverfilled epoxy. Thus, the structure can be attached to a PCB or othermounting board 210 which will have suitable traces (not shown) toreceive the source and gate electrodes 32, 33, while the posts 46 mayalso be connected to drain contact patterns on board 210. Referringspecifically to FIGS. 30 and 31, the posts 46 are insulated from theedges of die 30 by an insulation filler 103.

The gate and source 32, 33 and drain 46 are separated within thedie/board 210 bondline using a passivation process, similar to that usedin the previously described manufacturing process.

A device according to the present invention is not restricted to clipshaving fins for dissipating the generated heat; other heat dissipatingstructures may be utilized. For example, as shown by FIGS. 32a and 32b,according to another embodiment of the present invention, a clip havingan array of heat dissipating pins may be used to improve air flow. Eachpin in such a clip is a mesa type structure which is able to dissipateheat, but not restrict the flow of air across the heat emitting surface.

In order to improve the solderability of the clips to contacts on acircuit board, the clips may be coated with a material that can beeasily soldered such as, for example, nickel, nickel-gold,nickel-palladium or silver. In addition, the clips according to thepresent invention may be coated with a highly emissive coating toimprove heat dissipation by radiation.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

1. A semiconductor device comprising: a semiconductor die having a firstelectrode disposed on a first major surface thereof and a secondelectrode disposed on a second major surface thereof; an electricallyconductive web portion having a first major surface electricallyconnected to said first electrode; a plurality of heat conductivestructures extending away from a second major surface of said webportion, said second major surface of said web portion being opposite toits first major surface; and at least one conductive post extending froman edge of said web portion in a direction away from said first majorsurface of said web portion wherein said second electrode of saidsemiconductor die is adapted to be directly connected electrically andmechanically to a conductive pad and said conductive post includes aconnection surface for electrical and mechanical connection to anotherconductive pad so that said package semiconductor die may becomeexternally connectable to a substrate having said conductive pads with aconductive adhesive without the necessity for an auxiliary element forexternal connection.
 2. A semiconductor device according to claim 1,wherein said electrically conductive web portion is electricallyconnected to said first electrode by a layer of conductive adhesive. 3.A semiconductor device according to claim 2, wherein said conductiveadhesive comprises of solder.
 4. A semiconductor device according toclaim 2, wherein said conductive adhesive comprises of conductive epoxy.5. A semiconductor device according to claim 1, wherein said pluralityof heat conductive structures and said at least one conductive post areintegral with said electrically conductive web portion thereby forming aunitary body.
 6. A semiconductor device according to claim 5, whereinsaid unitary body comprises a thermally conductive material.
 7. Asemiconductor device according to claim 5, wherein said unitary bodycomprises one of aluminum and a metal matrix polymer.
 8. A semiconductordevice according to claim 1, further comprising at least anotherconductive post extending from another edge of said web portion in adirection away from said first major surface of said web portion.
 9. Asemiconductor device according to claim 1, wherein said semiconductordie is a power switching device.
 10. A semiconductor device according toclaim 9, wherein said power switching device is a MOSFET.
 11. Asemiconductor device according to claim 10, wherein said drain electrodeof said MOSFET is electrically connected to said web portion.
 12. Asemiconductor device according to claim 1 5, wherein said unitary bodycomprises one of copper and copper alloy.
 13. A semiconductor deviceaccording to claim 1, wherein each of said heat conductive structures isone of a fin and a pin.
 14. A semiconductor device comprising: asemiconductor die having a first electrode disposed on a first majorsurface thereof and a second electrode disposed on a second majorsurface thereof; an electrically conductive web portion having a firstmajor surface electrically connected to said first electrode; aplurality of heat conductive structures extending away from a secondmajor surface of said web portion, said second major surface of said webportion being opposite to its first major surface; at least oneconductive post extending from an edge of said web portion in adirection away from said first major surface of said web portion; and aninsulation filler disposed between said die and said at least oneconductive post.
 15. A semiconductor device comprising: a semiconductordie having a first electrode disposed on a first major surface thereofand a second electrode disposed on a second major surface thereof; anelectrically conductive web portion having a first major surfaceelectrically connected to said first electrode; a plurality of heatconductive structures extending away from a second major surface of saidweb portion, said second major surface of said web portion beingopposite to its first major surface; at least one conductive postextending from an edge of said web portion in a direction away from saidfirst major surface of said web portion; and a third electrode disposedon said second major surface of said die.
 16. A semiconductor devicecomprising: a semiconductor die having a first electrode disposed on afirst major surface thereof and a second electrode disposed on a secondmajor surface thereof; an electrically conductive web portion having afirst major surface electrically connected to said first electrode; aplurality of heat conductive structures extending away from a secondmajor surface of said web portion, said second major surface of said webportion being opposite to its first major surface; at least oneconductive post extending from an edge of said web portion in adirection away from said first major surface of said web portion; and athird electrode disposed on said second major surface of said die; apassivation layer disposed over at least portions of said secondelectrode and said third electrode of said semiconductor die.
 17. A clipcomprising: an electrically conductive web portion having a first majorsurface for adhesion and electrical connection to an electrode of asemiconductor die, and a second major surface opposite to said firstmajor surface; a plurality of fins connected to and extending away fromsaid second major surface of said electrically conductive web portion;and at least one conductive post connected to an edge of saidelectrically conductive web portion and extending away from said firstmajor surface; wherein said unitary body clip is comprised of a metalmatrix polymer.
 18. A clip according to claim 17, wherein said pluralityof fins and said at least one conductive post are integrally connectedto said electrically conductive web portion thereby forming a unitarybody.
 19. A clip according to claim 17, further comprising at leastanother conductive post connected to another edge of said electricallyconductive web portion and extending away from said first major surfaceof said web portion.
 20. A semiconductor device comprising: asemiconductor die having a first electrode disposed on a first majorsurface thereof and a second electrode disposed on a second majorsurface thereof; an electrically conductive web portion having a firstmajor surface electrically connected to said first electrode; aplurality of heat conductive structures thermally and mechanicallycoupled to a second major surface of said web portion, said second majorsurface of said web portion being opposite to its first major surface;and at least one conductive post extending from an edge of said webportion in a direction away from said first major surface of said webportion wherein said second electrode of said semiconductor die isadapted to be directly connected electrically and mechanically to aconductive pad and said conductive post includes a connection surfacefor electrical and mechanical connection to another conductive pad sothat said semiconductor die may become externally connectable to asubstrate having said conductive pads with a conductive adhesive withoutthe necessity for an auxiliary element for external connection.
 21. Asemiconductor device according to claim 20, wherein said electricallyconductive web portion is electrically connected to said first electrodeby a layer of conductive adhesive.
 22. A semiconductor device accordingto claim 21, wherein said conductive adhesive comprises of solder.
 23. Asemiconductor device according to claim 21, wherein said conductiveadhesive comprises of conductive epoxy.
 24. A semiconductor deviceaccording to claim 20, wherein said plurality of heat conductivestructures and said at least one conductive post are integral with saidelectrically conductive web portion thereby forming a unitary body. 25.A semiconductor device according to claim 24, wherein said unitary bodycomprises a thermally conductive material.
 26. A semiconductor deviceaccording to claim 24, wherein said unitary body comprises one ofaluminum and a metal matrix polymer.
 27. A semiconductor deviceaccording to claim 20, further comprising an insulation filler disposedbetween said die and said at least conductive post.
 28. A semiconductordevice according to claim 20, further comprising at least anotherconductive post extending from another edge of said web portion in adirection away from said first major surface of said web portion.
 29. Asemiconductor device according to claim 20, wherein said semiconductordie is a power switching device.
 30. A semiconductor device according toclaim 29, wherein said power switching device is a MOSFET.
 31. Asemiconductor device according to claim 30, wherein said drain electrodeof said MOSFET is electrically connected to said web portion.
 32. Asemiconductor device according to claim 20, wherein said semiconductordie further includes a third electrode disposed on said second majorsurface of said die.
 33. A semiconductor device according to claim 32,further comprising a passivation layer disposed over at least portionsof said second electrode and said third electrode of said semiconductordie.
 34. A semiconductor device according to claim 24, wherein saidunitary body comprises one of copper and copper alloy.
 35. Asemiconductor device according to claim 20, wherein said heat conductivestructures comprise fins.
 36. A semiconductor device according to claim20, wherein said heat conductive structures comprise pins.